Connecting method for structure with implantable electrodes

ABSTRACT

The invention concerns a method for connecting first contact studs ( 16 ) of a structure ( 1 ) bearing electrodes ( 4 ) for measuring or for stimulating a physiological activity with second studs ( 17 ) of at least a downstream circuit ( 2 ), each second stud ( 17 ) being traversed by an opening ( 15 ) perforating the downstream circuit. The method comprises the following steps: a) placing the downstream circuit on said structure, so that the opening ( 15 ) of a second stud ( 17 ) is located opposite a first stud ( 16 ); and b) depositing in the opening ( 15 ) of the second stud ( 17 ) a conductive material ( 18 ) providing the connection between the first and the second stud opposite.

[0001] The present invention relates to structures supporting electrodesintended to measure the electric activity of an organ or to stimulateit, and in particular to the connection of these structures to acircuit.

[0002] In FIG. 1, a structure 1 with electrodes is intended to beconnected to a downstream circuit 2. Structure 1 comprises an insulatingflexible support film 3. On film 3 are deposited electrodes 4 connectedby conductive tracks 5 to connection pads 6. The electrodes, the pads,and the tracks connecting them are formed by deposition and etching of aconductive layer on film 3. A thin insulating layer, not shown, coversthe structure, except for the electrodes and the pads. Structure 1 is aflexible structure of small thickness (from a few micrometers to a fewtens of micrometers), the electrodes of which are intended to be placedto contact an organ such as a nerve or the skin to measure the electricactivity of the organ or to stimulate it.

[0003] Structure 1 must be connected to circuit 2. Circuit 2 comprisespads 7, the arrangement of which corresponds to that of pads 6. Each pad7 is connected to a conductive track 8 for the conduction of the signalprovided to or by electrodes 4. To connect a pad 6 to a pad 7, a hole 10thoroughly crossing the structure is made in each of pads 6.

[0004] In FIG. 2, downstream circuit 2 is partially shown and a singlecontact pad 7 is visible. Structure 1 is here shown with support film 3,a single pad 6, and an upper insulating layer 11. The thickness ofcircuit 2, on the order of from one to two millimeters, is significantas compared to that of structure 1, which is at most a few tens ofmicrometers. Structure 1 is placed on circuit 2 so that each of holes 10is above a pad 7. The surface of each pad 7 is greater than that of ahole 10. A welding drop 12 is then deposited, by a conventional bondingtechnique well known in microelectronics, which fills hole 10 andoverflows on pad 6. Welding drop 12 ensures the electric contact betweenpads 6 and 7.

[0005] This way of doing has several disadvantages.

[0006] The electrode-supporting structure must be drilled into in themiddle of each pad 6. This operation is delicate, due to the fragilityof the structure, and this assumes that pads 6 are large enough, whichlimits their number. The drilling of pads 6 is generally performed bymeans of a laser beam, which results in having the metal layer formingthe pad partially split, so that the pad no longer exhibits a uniformsurface. The drilling of pads 0.6 may also be carried out by etching,which requires an additional mask, which brings about a cost problem,and greatly increases the pad drilling time.

[0007] Further, the impedance exhibited by this type of contact isrelatively high. Indeed, the surface of pad 6 enabling flowing of anelectric signal between pads 6 and 7 is a substantially ring-shapedsurface 13 delimited by the base of welding drop 12 and thecircumference of hole 10. The surface of pad 7 enabling flowing of theelectric signal is a substantially circular surface 14 equal to thesurface area of hole 10. Surfaces 13 and 14 have been shown in boldlines in FIG. 2. To avoid too much decreasing the impedance of thecontact between pads 6 and 7, surfaces areas 13 and 14 must besubstantially equal. As a result, at most, the surface area enablingflowing of an electric current between pads 6 and 7 is equal to half thesurface area of pad 6, which makes the impedance of the contact betweenpads 6 and 7 relatively high.

[0008] Further, welding 12 forms a brittle dome of relatively greatheight, typically on the order of 50 micrometers. This may hinder thecircuit encapsulation.

[0009] German patent application DE 19530353 A1 generally describes amethod for connecting contact areas of a flexible film to a printedcircuit. In this document, the printed circuit has pads drilled withmetallized holes, the metallization extending somewhat over the rearsurface of the integrated circuit which does not support the pads. Theportions of the film and of the circuit to be connected are opposite anda filler metal is deposited between them. Heat is provided to the rearcircuit surface, while a relatively high pressure is applied on theassembly formed by the film and the circuit. The provided heat melts thefiller metal, which forms a relatively thick gluing layer between thefilm and the circuit. The excess filler metal is absorbed by themetallized hole.

[0010] The abstract of Japanese patent JP 09312453 describes a techniquesimilar to that described in application DE 19530353.

[0011] The techniques described in the two above documents requireapplication of a high temperature and pressure. When such techniques aredesired to be applied to connect a structure support electrodes intendedto measure the electric activity of an organ or to stimulate it, severalproblems arise. Indeed, electrode structures are very thin and verybrittle. The application of a pressure, even mild, crushes the structureand may damage it. Further, the application of a high temperature,necessary to melt the filler metal, may destroy the structure. It willbe seen hereafter that the overthickness created by the welding layermay also be a disadvantage. An object of the present invention is toform a connection between an electrode structure intended to measure orstimulate an activity of physiological origin and a circuit, without fora high pressure to be exerted between the parts to be connected.

[0012] Another object of the present invention is to form a connectionbetween an electrode structure intended to measure or to stimulate anactivity of physiological origin and a circuit, without for a hightemperature to be applied to one of the parts to be connected.

[0013] Another object of the present invention is to form an easyconnection between an electrode structure intended to measure or tostimulate an activity of physiological origin and a circuit.

[0014] Another object of the present invention is to form a connectionenabling optimization of the contact impedance between an electrodestructure intended to measure or to stimulate an activity ofphysiological origin and a circuit.

[0015] Another object of the present invention is to form asubstantially planar connection between an electrode structure intendedto measure or to stimulate an activity of physiological origin and acircuit.

[0016] Another object of the present invention is to form a connectionbetween an electrode structure intended to measure or to stimulate anactivity of physiological origin and a circuit enabling optimal use ofthe surface area of the structure and/or of the circuit.

[0017] To achieve these and other objects, the present inventionprovides a method for connecting first pads of an electrode-supportingstructure capable of measuring or of stimulating an activity ofphysiological origin to second pads of at least one downstream circuit,each second pad being run through by an opening perforating thedownstream circuit, comprising the steps of:

[0018] a) placing the downstream circuit on said structure, so that theopening of the second pad is placed opposite to a first pad; and

[0019] b) depositing in the opening of the second pad a conductivematerial ensuring the connection between the second pad and the firstopposite pad.

[0020] According to an embodiment of the present invention, the openingmade in the second pad has a surface area substantially equal to thesurface area of the first opposite pad.

[0021] According to an embodiment of the present invention, the portionof said structure comprising the first pads is cut to form bladeterminals, and the connection of the second pads to the first pads issuch that the first pads of two adjacent blade terminals at least areconnected to second pads of different downstream circuits, arrangedsubstantially one above another.

[0022] According to an embodiment of the present invention, the openingperforating the downstream circuit is a metallized hole.

[0023] According to an embodiment of the present invention, theconnection of the first pads to the second pads is made by means of aconductor glue, of a conductor paste, or of a welding.

[0024] According to an embodiment of the present invention, the secondpad has a thickness on the order of from 20 to 50 micrometers and thefirst pad has a thickness equal to at most a few micrometers.

[0025] The present invention also provides a structure supportingelectrodes capable of measuring or of stimulating an activity ofphysiological origin exhibiting first pads likely to be connected tosecond pads of downstream circuits by a method according to the presentinvention. The portion of said structure comprising the first pads iscut to form blade terminals each supporting first pads.

[0026] The present invention also provides a structure supportingelectrodes capable of measuring or of stimulating an activity ofphysiological origin exhibiting first pads that can be connected tosecond pads of at least one downstream circuit by a method according tothe present invention, the first pads being connected to the electrodesby conductive tracks. Said conductive tracks are arranged on at leasttwo superposed levels separated by insulating layers, and at least oneconductive track runs under a first pad.

[0027] The present invention also provides an assembly formed of astructure supporting electrodes capable of measuring or of stimulatingan activity of physiological origin and a downstream circuit, whereinthe electrode-supporting structure and the downstream circuit areconnected by an above method.

[0028] In an embodiment of the present invention, the portion of theelectrode-supporting structure that comprises pads and at least theportion of the downstream circuit that is connected to said structureare covered with a biocompatible sheath.

[0029] The foregoing objects, features, and advantages of the presentinvention will be discussed in detail in the following non-limitingdescription of specific embodiments in connection with the accompanyingdrawings, in which:

[0030]FIG. 1, previously described, shows an electrode structure and adownstream circuit;

[0031]FIG. 2 shows a known type of connection between an electrodestructure and a downstream circuit;

[0032]FIG. 3A shows the connection of an electrode structure and of adownstream circuit according to a first embodiment of the presentinvention;

[0033]FIG. 3B shows the connection of an electrode structure and of adownstream circuit according to a second embodiment of the presentinvention;

[0034]FIGS. 4A and 4B respectively show a novel electrode structure andits mode of connection to a downstream circuit according to a thirdembodiment of the present invention;

[0035]FIG. 5 shows a novel electrode structure illustrating an advantageof the connection according to the present invention; and

[0036]FIGS. 6 and 7 show examples of application of a connectionaccording to the present invention.

[0037] In the drawings, same reference numerals represent same elements.The scales have not been respected, especially regarding thicknesses.

[0038]FIG. 3A shows a first embodiment of the present invention. The endof an electrode structure 1 of the above-mentioned type comprises aninsulating support film 3, a pad 16, and an upper insulating layer 11. Acircuit 2 comprising a pad 17 to be connected to pad 16 is here placedabove structure 1. Circuit 2 comprises an opening 15 which completelycrosses it, substantially located at the center of pad 17. In theexample shown, opening 15 has a size substantially equal to that of pad16. Opening 15 is filled with a material 18 ensuring the electricconnection of pads 16 and 17. Material 18 is preferably a conductivepaste or glue, but it may also be a welding. For example, a drop ofconductive glue is deposited in opening 15 and set by means ofultraviolet rays. Material 18 fills opening 15 and has a substantiallyplanar surface which very slightly extends beyond the surface of circuit2.

[0039] According to the present invention, circuit 2 is placed abovestructure 1, rather than the opposite as in FIG. 2. This has manyadvantages.

[0040] First, in the present invention, the drilling is performed incircuit 2 and not in structure 1. Now, circuit 2 is generally muchthicker than structure 1 (typically a hundred times as thick) and it ismuch easier to regularly drill into circuit 2 than structure 1. Further,the conductive layer forming pads 17 often is much thicker than theconductive layer forming pads 16, and it is accordingly much lessbrittle (typically, the thickness of a pad 17 is on the order of from 20to 50 micrometers while the thickness of a pad 16 is of a fewmicrometers at most, or even under one micrometer). The holes of circuit2 may be formed by means of various techniques, like by means ofconventional mechanical drilling techniques, and they are more regular.The holes of circuit 2 may also be formed before deposition of theconductive layer forming pads 17. This enables, for example, using alaser beam drilling without risking to damage pads 17.

[0041] Further, the fact that the thickness of pad 17 is generally muchgreater than that of pad 16 plays a role for the connection impedance.Indeed, the surface area of cylindrical crown 19 (in bold lines in FIG.3A) corresponding, in opening 15, to the thickness of pad 17, issignificant and non-negligibly takes part in the flowing of the electriccurrent. As an example, it is assumed that pads 16 and 17 have a sameradius R and that thickness e of pad 17 is also equal to R. If anopening 15 that represents 75% of the surface area of pad 17 isselected, the surface area of pad 16 taking part in the currentconduction is 0.75.πR². Cylindrical surface 19 represents, as foritself, approximately 1.7.πRe, and thus 1.7.πR², that is, twice as much.Since pads 16 and 17 generally have a small radius (typically some tenmicrometers), thickness e is generally greater than the pad radius and,as concerns pad 17, it is the thickness which mainly takes part in thecurrent flowing. As a result, connection material 18 needs not widelyextend over pad 17 and pad 17 needs not have a large surface area, whichoptimizes the used surface area. Further, if need be, material 18 maysignificantly overflow over the conductive layer which, in circuit 2,leads to pad 17. Also, pad 17 may, if desired, be simply formed by aportion of a conductive track of circuit 2, pierced by an opening 15.

[0042] Further, in the present invention, connection material 18 fillsthe hole defined by opening 15, which generally is a deep hole,conversely to hole 10 of FIG. 2. As a result, a sufficient quantity ofconductive material is systematically used and forms strong connections,without forming a significant dome as in FIG. 2. It should further benoted that it is possible to scrape material 18 from the surface ofcircuit 2 and obtain a practically planar surface of circuit 2.

[0043] As compared to the connections described in documents DE 19530353and JP 09312453, the connection of FIG. 3A has required no applicationof an excessive pressure or heat. Indeed, structure 1 and circuit 2 aresimply placed against each other during the connection and maintained inplace with no excessive pressure during the connection. If need be,structure 1 may be glued to circuit 2 by means of a thin insulatinglayer of insulating glue which does not cover pads 16.

[0044]FIG. 3B shows a second embodiment of the present invention. InFIG. 3B, a conductive track 20 of circuit 2 ends on opening 15 of pad17. The hole defined by opening 15 is metallized. A conductive layer 22covers the walls of opening 15. Layer 22 may, as shown, slightlyoverflow over the surface of circuit 2, but this is not necessary. Pad17 is thus defined by conductive layer 22, connected to track 20. Inthis embodiment, the surface area of pad 17 taking part in the electriccurrent conduction is very large. Connection material 18 needs not fillthe entire opening 15 to ensure a good mechanical strength and a goodconduction of the connection. The surface of circuit 2 remains planar.This embodiment enables particularly significant decrease in theimpedance of the formed connection and pad 17 takes up no more spacethan opposite pad 16. This is a significant advantage, especially whenmany pads 16 are arranged on a reduced surface of structure 1.

[0045]FIGS. 4A and 4B illustrate a third embodiment of the presentinvention, which enables a great versatility, and forming pads 17 oflarge size.

[0046]FIG. 4A shows a novel structure of electrodes 1′. In FIG. 4A, theend of structure 1′ comprises eight pads 16-i, with i ranging from 1 to8. The end of the structure is cut by three longitudinal openings 24separating pads 16-i in groups of two. Openings 24 thus divide the endof structure 1′ into four longitudinal blade terminals A, B, C, D,arranged in this order and comprising two pads each.

[0047]FIG. 4B illustrates the way of connecting structure 1′. Structure1′ is connected to two downstream circuits 2 a and 2 b. Non-adjacentblade terminals A and C are connected to circuit 2 a in the waydescribed in relation with FIG. 3A or 3B. Similarly, non-adjacent bladeterminals B and D are connected to circuit 2 b in the way described inrelation with FIG. 3A or 3B.

[0048] Circuits 2 a and 2 b are arranged one above the other. Theinsulating support film of structure 1 may by itself ensure the electricinsulation between circuits 2 a and 2 b, or an additional insulator suchas an insulating sheet will separate circuits 2 a and 2 b.

[0049] By so operating, a stacking of circuits 2 a and 2 b is formed.Pads 17 of each of circuits 2 a or 2 b may have a surface area which isdouble that of pads 16-i and extend over the width of two bladeterminals A, B, C, D. Thus, for example, pad 17 connected to pad 16-1 ofblade terminal A may take up a surface area corresponding to pad 16-1and to pad 16-3 of blade terminal B. It will easily exhibit an opening15 of same surface area as pad 16-1.

[0050] This connection mode is advantageous. For example, the pads ofstructure 1′ may be twice as small and thus twice as many as in priorart, or the width of structure 1′ may be twice as small. The obtainedassembly forms a very versatile compact assembly, practical to arrange.“Circuits 2 a and 2 b” is used to designate either two separatedownstream circuits, coupled or not, or merely two superposed elementsof a multiple-stage three-dimensional connector, associated with asingle downstream circuit.

[0051] Of course, the present invention is likely to have variousalterations, modifications, and improvements which will readily appearto those skilled in the art. In particular, the electrode-supportingstructure has been described as having an elongated shape, withelectrodes at one end and pads at the other end. However, the structuremay have any shape, for example, a circular shape, and the electrodesand pads of the structure may be arranged in any part of the structure.Also, the pads may be in any number in the structure, for example, asmany as several hundreds.

[0052] It should be noted that the connection method of the presentinvention applies for a diversity of thicknesses of theelectrode-supporting structure and of circuit 2.

[0053] It should also be noted that pads 17 may have any shape.

[0054] Also, in the connection mode illustrated in relation with FIGS.4A and 4B, the structure may be cut into a number of blade terminalsdifferent from four and the number of downstream circuits or ofsuperposed elements of a connector of the down-stream circuit may begreater than two. Also, even though each of the blade terminals of FIG.4A is shown with a single row of pads, the blade terminals may compriseseveral rows of pads, for example, two. Also, it is not necessary forall adjacent blade terminals to be connected to different downstreamcircuits. For example, blade terminals A and D of FIG. 4B may beconnected to circuit 2 a and blade terminals B and C to circuit 2 b,providing the same advantages as those mentioned in relation with FIG.4B.

[0055] It should also be noted that other advantages of the connectionmethod according to the present invention will occur to those skilled inthe art. For example, in the case where the structure comprises not oneelectrode layer, but several, the present invention has a significantadvantage.

[0056]FIG. 5 shows a structure 1″ with two electrode layers. Supportfilm 3 of structure 1″ is covered with a first conductive layer 30.Layer 30 is etched to form, at one end of the structure, a pad 16 aconnected by a conductive track 31 to an electrode not shown. On layer30 is an insulating layer 32. On layer 32 is arranged a secondconductive layer 34. Layer 34 is etched to form a pad 16 b, connected bya conductive track 35 to an electrode not shown. Layer 34 is topped withan insulating layer 36. Layers 32 and 36 are properly etched to exposepads 16 a and 16 b. Pad 16 a and track 31 are located at a level lowerthan pad 16 b and track 35. In prior art, as described in relation withFIG. 2, since pads 16 a and 16 b must be drilled into with perforatingholes, layer 31 cannot be located under pad 16 b, unless track 31follows a complicated path and a complex mask is used to etch it. Thesurface area required to form track 31 may then be relatively large. Inthe present invention, track 31 may run under pad 16 b and berectilinear. The structure surface is better used and the mask used forthe etching of layer 31 is simpler.

[0057] Finally, the connection according to the present invention mayhave various applications. For example, as illustrated in FIG. 6, theelectrode structure may be connected to another flexible structure, andnot to a rigid downstream circuit.

[0058] In FIG. 6, an electrode structure 1 having its layer 38supporting electrodes and connection pads shown in bold lines, isconnected to a flexible film 40, playing the role of a downstreamcircuit. Film 40 comprises an insulating base 41 and, at its uppersurface, a conductive layer 42 in which are formed the pads to beconnected to the pads of layer 38. The connection between structure 1and pad 40 is formed by means of the connection method according to thepresent invention, and the pads of structure 1 and of film 40 are notshown for simplicity. A biocompatible sheath 46 surrounds film 40, or atleast the portion of film 40 intended to contact one or several organs,and the portion of structure 1 comprising the pads.

[0059] The example of FIG. 6 is particularly advantageous. Indeed,structure 1, to be placed at the contact of an organ, is biocompatibleand its selfcost is high. Further, the manufacturing of structure 1 isperformed by deposition of layers on a mother wafer, and it isadvantageous to simultaneously form the largest possible number thereof.Thus, it is advantageous to form relatively short structures 1(typically, on the order of 2 centimeters). Now, in certainapplications, the organ to be tested or stimulated is at anon-negligible depth of the body surface. For example, in surgery of thebase of the skull (retrosigmoid approach), the acoustic nerve is locatedat a 5-centimeter depth and a short electrode structure does not reachit. In FIG. 6, the assembly formed by structure 1 and film 40 may berelatively long, for example, it may reach 20 cm, and biocompatiblesheath 46 enables introduction of the assembly to the desired depth.Further, the assembly of FIG. 6 is relatively inexpensive. Indeed, thematerials covered by the biocompatible sheath need not be biocompatibleand have a lesser cost.

[0060] In the example of FIG. 6, it is advantageous to keep thethickness of the assembly formed by structure 1 and film 40 as small aspossible. With the connection method according to the present invention,structure 1 and film 40 may be arranged directly against each other,with no gluing layer in between, the pads of structure 1 and of film 40being on opposite surfaces. This is an advantage with respect topreviously-mentioned prior art documents DE 19530353 and JP 09312453.Indeed, in these two documents, the pads to be interconnected face oneanother, conversely to the present invention, and a welding layerforming a relatively thick gluing layer is present between the thinstructure and the thick structure. In the present invention, if forexample a structure from 1 to 3 microns and a 20-micron film 40 areused, the assembly of structure 1 and of film 40 has a 23-micronthickness. The addition of a bonding layer, as in documents DE 19530353and JP 09312453, between structure 1 and film 40, would considerablyincrease the thickness of the assembly formed by the structure and thefilm, which can make it inoperative in certain applications. Further,the presence of a rigid and brittle gluing layer may be a disadvantage(lack of flexibility, risk of connection breakage). Moreover, the factthat, in the present invention, the surface of the structure comprisingthe pads faces the surface of the downstream circuit devoid of padsleaves the surface of the downstream circuit comprising the pads free.This enables, for example, the downstream circuit to comprise many padsand many connection tracks without risking for these to form undesiredcontacts with the structure pads and/or tracks.

[0061]FIG. 7 illustrates another example of application of theconnection method according to the present invention. In FIG. 7, anelectrode structure 1, having a layer 38 supporting electrodes andconnection pads, is connected to one end of a rigid element 50supporting, on its upper surface 52, connection pads and metal tracks.The other end of rigid element 50 is connected to a flexible film ofsmall thickness 56, which supports connection pads on its upper surface58. The connections between rigid element 50 and, respectively,structure 1 and film 56, are formed according to the method of thepresent invention. Rigid element 50 may be relatively short, forexample, 5 mm. A biocompatible sheath 60 surrounds film 56, rigidelement 50 and the portion of structure 1 supporting the pads. As inFIG. 6, sheath 60 enables connecting structure 1 to a relatively longflexible film, the assembly being biocompatible and relativelyinexpensive. Element 50 may have various functions. For example, thesurgeon may seize it by means of pliers to more easily introduce thestructure. Element 50 may also be used, after the placing of thestructure, to attach the assembly to the operating theatre napkin.Element 50 needs not be made of a biocompatible material. It may havevarious thicknesses, for example, on the order of 50 micrometers.Further, the masks of manufacturing of element 50 need not be asaccurate as those used in the manufacturing of structure 1 and they areaccordingly less expensive.

[0062] It has already been signaled that no high pressure needs beexerted for the connection according to the present invention of anelectrode structure to a downstream circuit. This is particularlyadvantageous in certain cases, for example, where the electrodestructure exhibits protruding elements at the pads, for example,elements having a 20-micron thickness or more, made of a relatively softinsulating material, which would crush upon application of a highvoltage.

[0063] Finally, it should be noted that the electrode structuresdescribed in relation with FIGS. 4A and 5 may also be connected by anyother method without departing from the scope of the present invention.Also, an electrode structure resulting from a combination of thestructures of FIGS. 4A and 5, for example, a structure in which one orseveral blade terminals comprise pads connected to superposed tracks, ispart of the present invention.

1. A method for connecting first pads (16) of a structure (1, 1′, 1″)supporting electrodes (4) capable of measuring or of stimulating anactivity of physiological origin to second pads (17) of at least onedownstream circuit (2, 2 a, 2 b, 40, 50), each second pad (17) being runthrough by an opening (15) perforating the downstream circuit,comprising the steps of: a) placing the downstream circuit on saidstructure, so that the surface of the downstream circuit devoid of thesecond pads is in contact with the structure and that the opening (15)of a second pad (17) is placed opposite to a first pad (16); and b)depositing in the opening (15) of the second pad (17) a conductivematerial (18) ensuring the connection between the second pad and thefirst opposite pad.
 2. The method of claim 1, wherein the opening (15)made in the second pad (17) has a surface area substantially equal tothe surface area of the opposite first pad (16).
 3. The method of claim1, wherein the portion of said structure comprising the first pads iscut to form blade terminals (A, B, C, D), and wherein the connection ofthe second pads (17) to the first pads is such that the first pads(16-i) of two adjacent blade terminals at least are connected to secondpads of different downstream circuits (2 a, 2 b), arranged substantiallyone above another.
 4. The method of any of claims 1 to 3, wherein theopening (15) perforating the downstream circuit is a metallized hole. 5.The method of any of claims 1 to 4, wherein the connection of the firstpads to the second pads is made by means of a conductor glue, of aconductor paste, or of a welding.
 6. The method of any of claims 1 to 5,wherein the second pad (17) has a thickness on the order of from 20 to50 micrometers and the first pad (16) has a thickness equal to at most afew micrometers.
 7. A structure (1′) supporting electrodes (4) capableof measuring or of stimulating an activity of physiological originexhibiting first pads (16-i) likely to be connected to second pads (17)of downstream circuits (2 a, 2 b) by the method of claim 3,characterized in that the portion of said structure comprising the firstpads is cut to form blade terminals (A, B, C, D) each supporting firstpads.
 8. A structure (1″) supporting electrodes capable of measuring orstimulating an activity of physiological origin exhibiting first pads(16 a, 16 b) that can be connected to second pads (17) of at least onedownstream circuit (2, 2 a, 2 b) by the method of any of claims 1 to 6,the first pads (16 a, 16 b) being connected to the electrodes byconductive tracks (31, 35), wherein said conductive tracks (31, 35) arearranged on at least two superposed levels separated by insulatinglayers (32), characterized in that at least one conductive track (31)runs under a first pad (16 b).
 9. An assembly formed by a structure (1,1′, 1″) supporting electrodes (4) capable of measuring or of stimulatingan activity of physiological origin and a downstream circuit (2, 2 a, 2b, 40, 50), characterized in that the electrode-supporting structure andthe downstream circuit are connected by the method of any of claims 1 to6.
 10. The assembly of claim 9, characterized in that the portion of theelectrode-supporting structure that comprises pads and at least theportion of the downstream circuit that is connected to said structureare covered with a biocompatible sheath (46, 60).